it maybe damaged. i've quite alot of bad luck with these little
. i tried cleaning one and placed it back in an old psp, but it didn't solve the problem. in the end it had to be replaced, there hard to find, in fact the olny place i found a new one was at undercutter.co.uk, but they charge a fortune for them. however, once i fitted it, the psp analog worked fine. if after cleaning it, you find it still doesn't work, i'd recommend getting a new one.
if your able too, i was told you can get these cables from a old lcd tv. if you have a cheap old one lying about, crack that open and take a few from that. you may need to cut them to sizw but it does work.